scholarly journals Thrombin generation and fibrin clot structure after vitamin D supplementation

2019 ◽  
Vol 8 (11) ◽  
pp. 1447-1454 ◽  
Author(s):  
Marc Blondon ◽  
Emmanuel Biver ◽  
Olivia Braillard ◽  
Marc Righini ◽  
Pierre Fontana ◽  
...  
Keyword(s):  
Vitamin D ◽  
Vitamin D Deficiency ◽  
Thrombin Generation ◽  
Fibrin Clot ◽  
Clot Lysis ◽  
High Dose ◽  
Severe Vitamin ◽  
Lysis Time ◽  
Clot Structure ◽  
Clot Lysis Time

Objective Vitamin D deficiency is associated with increased risks of arterial and venous cardiovascular events. Hypothetically, supplementation with vitamin D may lead to a less prothrombotic phenotype, as measured by global coagulation assays and fibrin clot structure. Methods In this prospective cohort study, we enrolled adult outpatients attending the Primary Care Division of the Geneva University Hospitals with a severe vitamin D deficiency (25-hydroxyvitamin-D3 (25-OHD) <25 nmol/L), excluding obese patients or with a recent acute medical event. We evaluated changes in coagulation times, thrombin generation assay, clot formation and clot lysis time, 25-OHD and parathormone before and 1–3 months after cholecalciferol oral supplementation with one-time 300,000 IU then 800 IU daily. Paired t-tests with a two-sided alpha of 0.05 compared absolute mean differences. Results The 48 participants had a mean age of 43.8 ± 13.8 years. After supplementation, 25-OHD levels increased from 17.9 ± 4.6 nmol/L to 62.5 ± 20.7 nmol/L 6.4 ± 3.0 weeks after inclusion. Endogenous thrombin potential and thrombin generation peak values both decreased significantly (−95.4 nM × min (95%CI −127.9 to −62.8), P < 0.001; −15.1 nM (−23.3 to −6.8), P < 0.001). The maximum absorbance by turbidimetry decreased significantly (P = 0.001) after supplementation. There was no change in clot lysis time, coagulation times or plasminogen activator inhibitor-1 and homocysteine levels. Conclusions In severe vitamin D deficiency, a high-dose cholecalciferol supplementation was associated with a reduction in thrombin generation and an average decreased number of fibrin protofibrils per fibers and fibrin fiber size measured by turbidimetry. This suggests that severe vitamin D deficiency may be associated with a potentially reversible prothrombotic profile.

Altered fibrin clot structure/function in patients with antiphospholipid syndrome: association with thrombotic manifestation

2014 ◽  
Vol 112 (08) ◽  
pp. 287-296 ◽  
Author(s):  
Magdalena Celińska-Löwenhoff ◽  
Teresa Iwaniec ◽  
Agnieszka Padjas ◽  
Jacek Musiał ◽  
Anetta Undas
Keyword(s):  
Structure Function ◽  
Antiphospholipid Syndrome ◽  
Thrombotic Event ◽  
Fibrin Clot ◽  
Clot Lysis ◽  
Lag Phase ◽  
Lysis Time ◽  
Clot Structure ◽  
Clot Lysis Time ◽  
D Dimer

SummaryWe tested the hypothesis that plasma fibrin clot structure/function is unfavourably altered in patients with antiphospholipid syndrome (APS). Ex vivo plasma clot permeability, turbidity and susceptibility to lysis were determined in 126 consecutive patients with APS enrolled five months or more since thrombotic event vs 105 controls. Patients with both primary and secondary APS were characterised by 11% lower clot permeability (p<0.001), 4.8% shorter lag phase (p<0.001), 10% longer clot lysis time (p<0.001), and 4.7% higher maximum level of D-dimer released from clots (p=0.02) as compared to the controls. Scanning electron microscopy images confirmed denser fibrin networks composed of thinner fibres in APS. Clots from patients with “triple-antibody positivity” were formed after shorter lag phase (p=0.019) and were lysed at a slower rate (p=0.004) than in the remainder. Clots from APS patients who experienced stroke and/or myocardial infarction were 8% less permeable (p=0.01) and susceptible to lysis (10.4% longer clot lysis time [p=0.006] and 4.5% slower release of D-dimer from clots [p=0.01]) compared with those following venous thromboembolism alone. Multivariate analysis adjusted for potential confounders showed that in APS patients, lupus anticoagulant and “triple-positivity” were the independent predictors of clot permeability, while “triple-positivity” predicted lysis time. We conclude that APS is associated with prothrombotic plasma fibrin clot phenotype, with more pronounced abnormalities in arterial thrombosis. Molecular background for this novel prothrombotic mechanism in APS remains to be established.

3309Complement activation leads to C3 and C5 dependent prothrombotic alterations of fibrin clots

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
K A Schutt ◽  
S Maxeiner ◽  
K Lysaja ◽  
M Berger ◽  
S Ruetten ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Complement Activation ◽  
Fibrin Clot ◽  
Complement C3 ◽  
Clot Lysis ◽  
Lysis Time ◽  
Patients With Diabetes ◽  
Clot Structure ◽  
Clot Lysis Time ◽  
Fibrin Clots

Abstract Background and aims Alterations of clot structure with thin fibres, small pores and prolonged fibrinolysis are associated with an increased cardiovascular risk. We previously demonstrated complement C3 to be incorporated into fibrin clots resulting in prolongation of fibrinolysis, an effect which was exaggerated in patients with diabetes. Patients with diabetes are known to display higher levels of complement activation. However, the role of complement activation in particular activation of C3 and C5 on clot lysis time remains unexplored. Thus, the present study seeks to determine whether activation of complement C3 and C5 by cobra venom factor (CVF) has an impact on fibrin clot structure and clot lysis. Materials and methods Fibrin clot structure and lysis were determined in a plasma pool of healthy controls in the presence and absence of the complement C3 and C5 activator CVF using a validated turbidimetric assay and scanning electron microscopy. C3 activation was inhibited by the addition of the small 14-AA-peptide Cp40, while C5 activation was blocked by the addition of the FDA approved monoclonal antibody eculizumab (Emab). Results Complement activation with CVF leads to a prothrombotic clot structure with thinner fibres (Co 0.20±0.001 au, CVF 0.13±0.001 au; p<0.0001) and prolongation of clot lysis time (Co 864±32 sec, CVF 1665±17 sec; p<0.0001), which was confirmed by electron microscopy (Co 94.7±1.44 nm, CVF 60.7±0.96 nm; p<0.0001). Inhibition of C3 activation by Cp40 improved clot structure resulting in thicker fibres (Co 0.20±0.001 au, CVF 0.13±0.001 au, CP40 0.20±0.002 au; p<0.0001) and shorter clot lysis time (Co 100%, CVF 181±8.9%, CP40 139±7.8%; p<0.0001), while scrambled protein had no effect on either clot structure or lysis time. As CVF can also activate C5 convertase we next investigated the inhibition of complement C5 activation with eculizumab. The latter improved both fibre thickness (Co 0.20±0.002 au, CVF 0.13±0.003 au, Emab 0.16±0.006 au; p<0.0001) and clot lysis time (Co 100%, CVF 192±12%, Emab 140±11%; p<0.001). The combined inhibition of C3 and C5 activation using both, Cp40 and eculizumab in combination optimized clot structure (Co 0.22±0.001 au, CVF 0.13±0.0006 au, Cp40/Emab 0.21±0.001 au; Co vs. Cp40/Emab p=0.003) and restored clot lysis time (Co 100%, CVF 226±6%, CP40/Emab 104±1%; Co vs. Cp40/Emap p=0.8). The results were confirmed by electron microscopy (fibre thickness: Co 93±1.4 nm, CVF 68±1.3 nm, Cp40 83±1.4 nm, Emab 78±1.7 nm, CP40/Emap 95±1.6 nm). Conclusions Complement activation at the level of complement C3 and C5 has a detrimental impact on clot properties. Blocking C3 and C5 activation can restore both clot density and prolongation of clot lysis time. Further studies are needed to determine the underlying binding sites on fibrin(ogen) to pave the way for molecules improving clot properties without affecting immune responses. Acknowledgement/Funding KS is supported by the German Research Foundation (DFG) (SFB/TRR219 C-07; HE 5666/1-2 to KS (née Hess)]

Plasma fibrin clot properties in the G20210A prothrombin mutation carriers following venous thromboembolism: the effect of rivaroxaban

2017 ◽  
Vol 117 (09) ◽  
pp. 1739-1749 ◽  
Author(s):  
Agnieszka Janion-Sadowska ◽  
Joanna Natorska ◽  
Jakub Siudut ◽  
Michal Zabczyk ◽  
Andrzej Stanisz ◽  
...  
Keyword(s):  
Venous Thromboembolism ◽  
Fibrin Clot ◽  
Clot Lysis ◽  
Mutation Carriers ◽  
Lysis Time ◽  
Prothrombin Mutation ◽  
Fibrinolysis Inhibitor ◽  
Heterozygous Carriers ◽  
Mutation Group ◽  
Clot Structure

SummaryWe sought to investigate whether the G20210A prothrombin mutation modifies plasma fibrin clot properties in patients after venous thromboembolism (VTE) and how rivaroxaban treatment affects these alterations. We studied 34 prothrombin mutation heterozygous carriers and sex- and age-matched 34 non-carriers, all at least three months since the first VTE episode, before and during treatment with rivaroxaban. Clot permeability (Ks) and clot lysis time (CLT) with or without elimination of thrombin activatable fibrinolysis inhibitor (TAFI) were assessed at baseline, 2–6 hours (h) after and 20–25 h after intake of rivaroxaban (20 mg/day). At baseline, the prothrombin mutation group formed denser clots (Ks −12 %, p=0.0006) and had impaired fibrinolysis (CLT +14 %, p=0.004, and CLT-TAFI +13 %, p=0.03) compared with the no mutation group and were similar to those observed in 15 healthy unrelated prothrombin mutation carriers. The G20210A prothrombin mutation was the independent predictor for Ks and CLT before rivaroxaban intake. At 2–6 h after rivaroxaban intake, clot properties improved in both G20210A carriers and non-carriers (Ks +38 %, and +37 %, CLT −25 % and −25 %, CLT-TAFI −20 % and −24 %, respectively, all p<0.001), but those parameters were worse in the prothrombin mutation group (Ks −12.8 %, CLT +17 %, CLT-TAFI +13 %, all p<0.001). Rivaroxaban concentration correlated with fibrin clot properties. After 20–25 h since rivaroxaban intake most clot properties returned to baseline. Rivaroxaban-related differences in clot structure were confirmed by scanning electron microscopy images. In conclusion, rivaroxaban treatment, though improves fibrin clot properties, cannot abolish more prothrombotic fibrin clot phenotype observed in prothrombin mutation carriers following VTE.

Biological Rational for the Use of Heparin in Septic Shock: Translational Data from the Halo Pilot RCT

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2336-2336
Author(s):  
Brett L. Houston ◽  
Dhruva J. Dwivedi ◽  
Peter Grin ◽  
Michelle Kwong ◽  
Enrico Rullo ◽  
...  
Keyword(s):  
Septic Shock ◽  
Protein C ◽  
Thrombin Generation ◽  
Activated Protein C ◽  
Plasminogen Activator Inhibitor ◽  
Clot Lysis ◽  
Plasminogen Activator Inhibitor 1 ◽  
Lysis Time ◽  
Activator Inhibitor ◽  
Clot Lysis Time

Abstract BACKGROUND: Sepsis is a leading cause of mortality among critically ill patients and is associated with both systemic inflammation and up-regulation of coagulation. In the translational sub-study of the HALO (Heparin AnticoaguLation to improve Outcomes in septic shock) pilot trial, we evaluated the mechanisms by which unfractionated heparin (UFH) may reduce inflammation and coagulation in patients with septic shock. METHODS: In this multicenter pilot randomized trial of 69 patients diagnosed with septic shock, we evaluated the feasibility of administering therapeutic dose intravenous UFH (18 IU/kg/hr) compared to thromboprophylactic subcutaneous dalteparin (5000 IU daily). Blood samples were collected on days 1 (baseline prior to study infusion), 2, 3, 5, and 7. We evaluated coagulation using assays for protein C, activated protein C, thrombin-antithrombin (TAT), thrombin generation, clot lysis, plasminogen activator inhibitor-1 (PAI-1) and cell-free DNA (cf-DNA). Systematic inflammation was evaluated by measuring inflammatory cytokines (interleukin (IL)-6, IL-8, IL-10, and IL-17). RESULTS: The mean age of the study population was 61 years, of whom 43% were male. Thirty two patients (46%) were randomized to receive unfractionated heparin while 37 (54%) received dalteparin. The baseline mean aggregate Acute Physiology and Chronic Health Evaluation II (APACHE II) score was 25 ± 7.8, and Multiple Organ Dysfunction Score (MODS) 5.6 ± 2.38. Baseline laboratory testing (coagulation assays and inflammatory cytokines) was not statistically different between UFH vs. LMWH treated patients. On day 2, the median clot lysis time in UFH-treated patients compared to those receiving dalteparin was significantly decreased [6630 (IQR 0 - 14156) seconds vs. 9615 (IQR 8209 - 11018) seconds; p = 0.008] (Figure 1). UFH administration was associated with increased protein C levels [66.4% of normal (IQR 9.9 - 122.9) vs. 41.1% of normal (IQR 4.8 - 77.4); p = 0.02], and reduced thrombin generation of 0 (IQR 0 - 1725) units/min vs. 3393 (IQR 0 - 8519) units/min; p<0.001]. On day 2, we observed no differences between thrombin-antithrombin complex (TAT), activated protein C, plasminogen activator inhibitor-1 (PAI-1) or cell-free DNA (cf-DNA). Similarly, there were no differences between treatment groups in inflammatory markers, including IL-6, IL-8, IL-10 or IL-17. Analysis thus far is limited to samples collected on days 1 and 2; day 3-7 analyses are ongoing. CONCLUSION: In patients diagnosed with septic shock, IV UFH reduces thrombin generation, shortens clot lysis time and improves endogenous protein C levels compared to dalteparin administered for thromboprophylaxis. Analyses for samples obtained on days 3, 5 and 7 are ongoing. These preliminary data provide a biologic rational for the use of heparin in sepsis. Figure 1. Differences in clot lysis, protein C and thrombin generation in patients treated with UFH vs. LMWH. UFH is associated with reduced thrombin generation, improved Protein C levels, and reduced clot lysis time. Figure 1. Differences in clot lysis, protein C and thrombin generation in patients treated with UFH vs. LMWH. UFH is associated with reduced thrombin generation, improved Protein C levels, and reduced clot lysis time. Disclosures No relevant conflicts of interest to declare.

scholarly journals BβArg448Lys polymorphism is associated with altered fibrin clot structure and fibrinolysis in type 2 diabetes

2017 ◽  
Vol 117 (02) ◽  
pp. 295-302 ◽  
Author(s):  
Katie A. Greenhalgh ◽  
Mark W. Strachan ◽  
Saad Alzahrani ◽  
Paul D. Baxter ◽  
Kristina F. Standeven ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Fibrin Clot ◽  
Clot Lysis ◽  
Plasma Clot ◽  
Lysis Time ◽  
Increased Risk ◽  
Fibrin Network ◽  
Clot Lysis Time ◽  
Fibrin Clots

SummaryBoth type 2 diabetes (T2DM) and Bß448Lys variant of fibrinogen are associated with dense fibrin clots, impaired fibrinolysis and increased cardiovascular risk. It was our objective to investigate whether BßArg448Lys adds to vascular risk by modulating fibrin network structure and/or fibrinolysis in diabetes. The primary aim was to study effects of BßArg448Lys on fibrin network characteristics in T2DM. Secondary aims investigated interactions between gender and BßArg448Lys substitution in relation to fibrin clot properties and vascular disease. Genotyping for BßArg448Lys and dynamic clot studies were carried out on 822 T2DM patients enrolled in the Edinburgh Type 2 Diabetes Study. Turbidimetric assays of individual plasma samples analysed fibrin clot characteristics with additional experiments conducted on clots made from purified fibrinogen, further examined by confocal and electron microscopy. Plasma clot lysis time in Bß448Lys was longer than Bß448Arg variant (mean ± SD; 763 ± 322 and 719 ± 351 seconds [s], respectively; p<0.05). Clots made from plasma-purified fibrinogen of individuals with Arg/Arg, Arg/Lys and Lys/Lys genotypes showed differences in fibre thickness (46.75 ± 8.07, 38.40 ± 6.04 and 25 ± 4.99 nm, respectively; p<0.001) and clot lysis time (419 ± 64, 442 ± 87 and 517 ± 65 s, respectively; p=0.02), directly implicating the polymorphism in the observed changes. Women with Bß448Lys genotype had increased risk of cerebrovascular events and were younger compared with Bß448Arg variant (67.2 ± 4.0 and 68.2 ± 4.4 years, respectively; p=0.035). In conclusion, fibrinogen Bβ448Lys variant is associated with thrombotic fibrin clots in diabetes independently of traditional risk factors. Prospective studies are warranted to fully understand the role of BβArg448Lys in predisposition to vascular ischaemia in T2DM with the potential to develop individualised antithrombotic management strategies.

scholarly journals The Hypofibrinolytic Defect of Nephrotic Syndrome Is Directly Proportional to Fibrin Network Density

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1218-1218
Author(s):  
Amanda P. Waller ◽  
Katelyn J Wolfgang ◽  
Bryce A. Kerlin
Keyword(s):  
Nephrotic Syndrome ◽  
Disease Severity ◽  
Diphtheria Toxin ◽  
Thrombin Generation ◽  
Fibrin Clot ◽  
Network Density ◽  
Clot Lysis ◽  
Plasma Clot ◽  
Fibrin Network ◽  
Clot Structure

Abstract Introduction Nephrotic syndrome (NS) is characterized by massive proteinuria (secondary to podocyte injury), hypoalbuminemia, and edema. Importantly, NS is associated with a complex acquired hypercoagulopathy and a high incidence (~25%) of life-threatening thrombotic complications. Both hypercoagulopathy and hypofibrinolysis are described contributors to NS-related VTE risk. However, the mechanisms underlying the latter are poorly understood. We previously showed NS disease severity is directly proportional to both hypercoagulopathy and fibrinolytic resistance There is evidence that fibrin clot structural density contributes to clot stability and has been observed in the presence of both increased plasma thrombin generation and fibrinogen levels, both of which we have previously demonstrated in NS. Thus the aim of the present study was to investigate the mechanistic relationship between fibrin clot structure and fibrinolysis using two rodent models of NS and a cohort of human NS patients. We hypothesized that hypofibrinolysis arises from increased fibrin network density in a manner directly proportional to NS disease severity. Methods Using two well-established rat models of NS, transgenic diphtheria toxin receptor (DTR) and puromycin aminonucleoside (PAN), we compared fibrinolytic markers to disease severity. A range of severity was induced by a single injection of diphtheria toxin (0-75 ng/kg IP) or PAN (0-150 mg/kg IV). On day 10 post-injection, morning spot urines were collected and analyzed for protein:creatinine ratio (uPr:Cr). Rats were then anesthetized and venous blood (IVC) was collected into 0.32% NaCitrate/1.45 µM Corn Trypsin Inhibitor and spun down to platelet poor plasma (PPP). Samples were also collected from a local cohort of pediatric and adult NS patients (n=23), along with the corresponding clinical lab data for each patient. Plasma clot lysis assay (CLA) was performed using urokinase (50 IU) +/- plasminogen (2.4 uM), on clots initiated with high (20 nM) or low (5 nM) thrombin. Clot fibrin network structure was visualized/assessed by laser scanning confocal microscopy using fluorescently-labeled fibrinogen as a tracer. Fibrinolytic markers in plasma were measured by ELISA. Results Hypofibrinolysis: Previous findings of a hypofibrinolytic defect was confirmed with the CLA, such that plasma clot lysis at 60 min was significantly negatively correlated with proteinuria (R2=0.196; P=0.007 & R2=0.214; P=0.010) and significantly positively correlated with hypoalbuminemia (R2=0.310; P<0.001 & R2=0.240; P=0.006), in the DTR & PAN models, respectively. Additionally, plasma clot lysis by CLA was decreased in NS patients with uPrCr ≥2 (n=16) vs. <2 mg/mg (n=7) (96.1 vs 55.2 %, respectively; P=0.041). Similar results were found when the assay was repeated using high or low thrombin concentrations or increased UK (200 IU), with and without the addition of physiologic amounts of plasminogen. When the assay was performed in the absence of UK (0 IU), lysis at 60 min was drastically reduced (~17%) with no difference between groups. Mechanisms of Hypofibrinolysis: Fibrin network density increased with disease severity such that it was positively correlated with proteinuria (P=0.022) and negatively correlated with hypoalbuminemia (P=0.01) in our DTR rat model, with similar results seen in our human samples (Figure). As expected, fibrin network density was negatively correlated with plasma clot lysis (P=0.04), while plasma fibrinogen concentration (P=0.017), and thrombin generation (P=0.047) were positively correlated with fibrin density. There was no correlation with plasma uPA, PAI-1, a2AP, tPA, TAFI, or plasminogen. Conclusions These data suggest that nephrotic plasma forms thrombi with a denser fibrin network that is resistant to fibrinolysis, in a manner that is proportional to disease severity. The significant correlation between thrombin generation and fibrin network density suggest that plasma thrombotic potential may be a key mechanism contributing to the altered clot structure and impaired clot lysis of NS. Current studies are exploring the mechanisms underlying and in vivo significance of fibrinolytic resistance in our rat NS models. Disclosures No relevant conflicts of interest to declare.

Abstract 16668: The Effects of Dabigatran on Fibrin Network Structure and Lysis: A Simple Technique to Monitor Efficacy of Treatment?

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Francesco Franchi ◽  
Rhodri King ◽  
Fladia Phoenix ◽  
Fabiana Rollini ◽  
Jung Rae Cho ◽  
...  
Keyword(s):  
Antiplatelet Therapy ◽  
Placebo Treatment ◽  
Fibrin Clot ◽  
Clot Formation ◽  
Clot Lysis ◽  
Lag Phase ◽  
Maximum Absorbance ◽  
Lysis Time ◽  
Fibrin Network ◽  
Clot Lysis Time

Background: Thrombus formation represent the final step in the atherothrombotic process and occurs secondary to a complex interaction between platelets and coagulation factors. Increased platelet reactivity and enhanced clot formation can both determine predisposition to vascular events. Direct platelet inhibition by modern antiplatelet therapy is now effective at controlling the cellular component of coagulation but the fibrin network is not generally targeted in arterial disease. Our aim was to investigate the effects of dabigatran on fibrin network characteristics in individuals dual antiplatelet therapy (DAPT). Methods: This was a prospective, randomized, double-blind study conducted in 30 patients on maintenance (at least 30 days) DAPT with aspirin (81mg/day) and clopidogrel (75mg/day). Patients were randomized to receive either dabigatran 150mg bid or matching placebo for 7 days. Fibrin clot properties were studied using a validated turbidimetric assay and the following parameters were recorded: lag phase and time to full clot formation, both of which measure clotting potential; clot maximum absorbance, representing fibrin network density and fibre thickness; clot lysis time to assess fibrinolytic efficiency. Results: Dabigatran treatment was associated with an increase in lag phase, compared with baseline, of 1013±167 sec , whereas no difference was detected in placebo treated patients (-17±14 sec, p<0.001 for dabigatran vs placebo). Similar results were obtained for clot formation time with an increase of 240±37 sec in dabigatran treated patients with no change following placebo treatment (-24±18 sec; p<0.001 comparing the two groups). The change in clot maximum absorbance after dabigatran and placebo treatment showed no differences (-0.02±0.01 and 0.00±0.01 au, respectively; p=0.2) and clot lysis time was similar. Conclusions: In patients on DAPT with aspirin and clopidogrel, additional treatment with dabigatran delays fibrin clot formation without affecting fibrinolysis. Therefore, triple therapy with dabigatran may be one option to reduce thrombosis potential in high risk individuals. Moreover, our assay, which can be conducted on stored samples, offers the opportunity to monitor response to dabigatran therapy.

Some Aspects of Fibrin Clot Lysis and Its Inhibition by Human Serum

1967 ◽  
Vol 18 (01/02) ◽  
pp. 101-113 ◽  
Author(s):  
M. J Gallimoke ◽  
J. T. B Shaw
Keyword(s):  
Sodium Chloride ◽  
Fibrin Clot ◽  
Chloride Ions ◽  
Clot Lysis ◽  
Irreversible Inhibitors ◽  
Zero Order Kinetics ◽  
Lysis Time ◽  
Kinetics Of ◽  
Clot Lysis Time ◽  
Fibrin Clots

SummaryThe lysis by plasmin of fibrin clots prepared from plasminogen-deficient fibrinogen, and by urokinase of similar clots prepared from plasminogen-rich fibrinogen has been studied. In a simple system containing no plasminogen the clot lysis time is inversely proportional to the concentration of added plasmin, and zero order kinetics are obeyed. The reciprocal of the lysis time is a measure of the fibrinolytic activity in the system, and may be used to study antiplasmins. When serum was included a reduction in reciprocal lysis time resulted, the extent of which varied linearly with the amount of serum added. These relationships persisted whether soluble or insoluble plasmin preparations were used and whether or not chloride ions were present. They indicate that serum antiplasmins behave as irreversible or pseudo-irreversible inhibitors. It was found that sodium chloride exerts a potentiating effect on fibrinolysis by plasmin, but does not influence the extent to which the enzyme is inhibited by serum antiplasmins.When fibrin clots were prepared from plasminogen-rich fibrinogen, and urokinase was included, a direct relationship was found to exist between the concentration of urokinase and the square of the reciprocal clot lysis time. When serum was added, vigorous inhibition of fibrinolysis resulted when sodium chloride was present; no inhibition was observed in its absence. It is proposed that sodium chloride weakens the interaction between plasminogen and fibrin in the clots, and renders the plasmin produced by the action of urokinase more susceptible to inhibition by antiplasmins. Evidence in support of this hypothesis is presented and the kinetics of fibrinolysis by plasmin, and its inhibition, are discussed.

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